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A platform for illuminating academic papers. We annotate and share a paper every week. Save, annotate and share papers with anyone: https://t.co/0o2Pls3jmo

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The Oldham coupling, invented in 1821 by John Oldham, is used to transfer torque between axles that don't exactly line up

The Oldham coupling, invented in 1821 by John Oldham, is used to transfer torque between axles that don't exactly line up

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WWII story: When Nazis invaded Copenhagen, chemist George de Hevesy dissolved two Nobel Prize gold medals in acid rather than let them be stolen. The orange solution sat unnoticed on a lab shelf throughout the occupation. After the war, he recovered the gold & the medals were reminted. 🏅

WWII story: When Nazis invaded Copenhagen, chemist George de Hevesy dissolved two Nobel Prize gold medals in acid rather than let them be stolen. The orange solution sat unnoticed on a lab shelf throughout the occupation. After the war, he recovered the gold & the medals were reminted. 🏅

212,545 просмотров

Planetary Orbits visualized in the Heliocentric ☀️ and Geocentric 🌎 Systems.

Planetary Orbits visualized in the Heliocentric ☀️ and Geocentric 🌎 Systems.

176,023 просмотров

Revisiting this interesting story during Nobel Prize week: In the heart of World War II, as the Nazis took control of Copenhagen, a peculiar situation took place at the Institute of Theoretical Physics, led by physicist Niels Bohr. Two Nobel laureates Max von Laue and James Franck, fearing the confiscation of their gold Nobel Prize medals by the Nazis, had sent their medals to Bohr for safekeeping. On the day the Nazis arrived in Copenhagen, Hungarian chemist Georgy de Hevesy, who was working in Bohr's lab, devised a plan to prevent the discovery of the medals. Initially considering burying the medals, they quickly dismissed the idea, fearing the thorough searches the Nazis would conduct. Instead, de Hevesy proposed a chemical solution — literally. Utilizing a mixture known as "aqua regia" (a blend of hydrochloric and nitric acids), he set about dissolving the gold medals. This concoction is one of the few substances capable of dissolving gold, a notably unreactive element. As the Nazis marched outside, de Hevesy dissolved the precious medals, reducing them to a colorless solution that eventually turned bright orange. The liquid containing the dissolved gold was then placed on a high shelf in the laboratory, where it remained unnoticed throughout the Nazi occupation. Post World War II, upon returning to the laboratory after V-E Day, de Hevesy found the beaker undisturbed on the shelf. The gold was recovered from the solution and returned to the Nobel Prize committee, who then reminted the medals and presented them back to Laue and Franck in a ceremony in 1952.

Revisiting this interesting story during Nobel Prize week: In the heart of World War II, as the Nazis took control of Copenhagen, a peculiar situation took place at the Institute of Theoretical Physics, led by physicist Niels Bohr. Two Nobel laureates Max von Laue and James Franck, fearing the confiscation of their gold Nobel Prize medals by the Nazis, had sent their medals to Bohr for safekeeping. On the day the Nazis arrived in Copenhagen, Hungarian chemist Georgy de Hevesy, who was working in Bohr's lab, devised a plan to prevent the discovery of the medals. Initially considering burying the medals, they quickly dismissed the idea, fearing the thorough searches the Nazis would conduct. Instead, de Hevesy proposed a chemical solution — literally. Utilizing a mixture known as "aqua regia" (a blend of hydrochloric and nitric acids), he set about dissolving the gold medals. This concoction is one of the few substances capable of dissolving gold, a notably unreactive element. As the Nazis marched outside, de Hevesy dissolved the precious medals, reducing them to a colorless solution that eventually turned bright orange. The liquid containing the dissolved gold was then placed on a high shelf in the laboratory, where it remained unnoticed throughout the Nazi occupation. Post World War II, upon returning to the laboratory after V-E Day, de Hevesy found the beaker undisturbed on the shelf. The gold was recovered from the solution and returned to the Nobel Prize committee, who then reminted the medals and presented them back to Laue and Franck in a ceremony in 1952.

127,557 просмотров

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Freeman Dyson on the importance of cheap space travel

Freeman Dyson on the importance of cheap space travel

Fermat's Library

16,541,060 просмотров • 1 год назад

Andrew Wiles on the morning he discovered how to fix his proof of Fermat's Last Theorem

Andrew Wiles on the morning he discovered how to fix his proof of Fermat's Last Theorem

Fermat's Library

1,983,575 просмотров • 8 месяцев назад

American physicist Edward Witten explains why it wasn’t until Einstein's work that we fully understand the reason behind the inverse square law, and why it's specifically a square rather than some arbitrary decimal 1 / distance² vs. 1 / distance¹·⁷⁴⁸²²⋅⋅⋅

American physicist Edward Witten explains why it wasn’t until Einstein's work that we fully understand the reason behind the inverse square law, and why it's specifically a square rather than some arbitrary decimal 1 / distance² vs. 1 / distance¹·⁷⁴⁸²²⋅⋅⋅

Fermat's Library

390,726 просмотров • 1 месяц назад

AI pioneer John McCarthy reflects on AI’s earliest critics

AI pioneer John McCarthy reflects on AI’s earliest critics

Fermat's Library

43,521 просмотров • 9 дней назад

Dijkstra on why he believed programmers should stop using the term "bug"

Dijkstra on why he believed programmers should stop using the term "bug"

Fermat's Library

374,211 просмотров • 3 месяцев назад

Murray Gell-Mann, the Nobel prize-winning physicist, on contemplating suicide at 18 after getting into graduate school at MIT

Murray Gell-Mann, the Nobel prize-winning physicist, on contemplating suicide at 18 after getting into graduate school at MIT

Fermat's Library

148,059 просмотров • 1 месяц назад

As a droplet touches a liquid surface it bounces gently, kept afloat momentarily by a thin air cushion. As the air dissipates the droplet comes in contact with the liquid. The droplet undergoes a multi-step coalescence journey: with each interaction, it merges and reduces in size, transitioning into a smaller droplet, until it eventually fully merges with the liquid below.

As a droplet touches a liquid surface it bounces gently, kept afloat momentarily by a thin air cushion. As the air dissipates the droplet comes in contact with the liquid. The droplet undergoes a multi-step coalescence journey: with each interaction, it merges and reduces in size, transitioning into a smaller droplet, until it eventually fully merges with the liquid below.

Fermat's Library

685,425 просмотров • 2 лет назад

American physicist Edward Witten explains why it wasn’t until Einstein's work that we fully understand the reason behind the inverse square law, and why it's specifically a square rather than some arbitrary decimal 1 / distance² vs. 1 / distance¹·⁷⁴⁸²²⋅⋅⋅

American physicist Edward Witten explains why it wasn’t until Einstein's work that we fully understand the reason behind the inverse square law, and why it's specifically a square rather than some arbitrary decimal 1 / distance² vs. 1 / distance¹·⁷⁴⁸²²⋅⋅⋅

Fermat's Library

427,841 просмотров • 1 год назад

Marvin Minsky recalls how John Nash effortlessly solved his PhD problem

Marvin Minsky recalls how John Nash effortlessly solved his PhD problem

Fermat's Library

271,116 просмотров • 1 год назад

Why the last digit of n⁵ is equal to the last digit of n 2⁵=32 4⁵=1024 5⁵=3125

Why the last digit of n⁵ is equal to the last digit of n 2⁵=32 4⁵=1024 5⁵=3125

Fermat's Library

347,127 просмотров • 2 лет назад

Computer scientist Edsger Dijkstra on the frustration of debugging a program you wrote yourself

Computer scientist Edsger Dijkstra on the frustration of debugging a program you wrote yourself

Fermat's Library

229,533 просмотров • 1 год назад

Freeman Dyson on how he struggled to learn quantum mechanics from Paul Dirac

Freeman Dyson on how he struggled to learn quantum mechanics from Paul Dirac

Fermat's Library

153,922 просмотров • 1 год назад

"There are only two kinds of modern math books: Those you cannot read beyond the first sentence, and those you cannot read beyond the first page" - C.N. Yang (Nobel laureate in Physics)

"There are only two kinds of modern math books: Those you cannot read beyond the first sentence, and those you cannot read beyond the first page" - C.N. Yang (Nobel laureate in Physics)

Fermat's Library

76,984 просмотров • 1 год назад

At Princeton, Feynman became obsessed with this question: What happens when a sprinkler sucks in water instead of spraying it out? Seems simple, but the physics is surprisingly subtle.

At Princeton, Feynman became obsessed with this question: What happens when a sprinkler sucks in water instead of spraying it out? Seems simple, but the physics is surprisingly subtle.

Fermat's Library

61,155 просмотров • 10 месяцев назад

How to get a fair coin flip with an unfair coin 🪙

How to get a fair coin flip with an unfair coin 🪙

Fermat's Library

77,843 просмотров • 1 год назад

Feynman on solving hard problems

Feynman on solving hard problems

Fermat's Library

85,021 просмотров • 1 год назад

Feynman on the Scientific Method

Feynman on the Scientific Method

Fermat's Library

98,644 просмотров • 1 год назад

A one-line proof of the infinitude of primes

A one-line proof of the infinitude of primes

Fermat's Library

69,126 просмотров • 1 год назад

Bernard Chazelle proved that if each bird adjusts its velocity and position to the other birds within a fixed radius, the time it takes to converge to a steady state tends to infinity as the number of birds increases.

Bernard Chazelle proved that if each bird adjusts its velocity and position to the other birds within a fixed radius, the time it takes to converge to a steady state tends to infinity as the number of birds increases.

Fermat's Library

104,661 просмотров • 2 лет назад

Freeman Dyson on the Greening of the Galaxy: "the galaxy is very boring as long as it's dead, you look at all these planets and stars we've discovered, they're beautiful, but still they're sort of boring. So I'd like to bring life to the universe and bring the universe to life"

Freeman Dyson on the Greening of the Galaxy: "the galaxy is very boring as long as it's dead, you look at all these planets and stars we've discovered, they're beautiful, but still they're sort of boring. So I'd like to bring life to the universe and bring the universe to life"

Fermat's Library

36,426 просмотров • 8 месяцев назад